Quantifying adapted balance control during walking in chronic stroke - PROJECT SUMMARY Post-stroke balance and gait impairments are a barrier to safe community ambulation for those with chronic stroke. Although an important aspect of post-stroke rehabilitation is restoring a person’s ability to safely ambulate in their community, many post-stroke individuals discharged from rehabilitation are still unable to manage the varied demands of community ambulation. Our premise is that walking adaptability and the control of balance during walking are interrelated factors that can be addressed to improve post-stroke rehabilitation. Walking adaptability is assessed by the performance of complex walking tasks, defined as tasks that increase motor and cognitive demands to a greater extent than simple overground walking. Although gait is a task with concomitant demands on balance and mobility, studies of post-stroke walking adaptability have largely ignored the mechanisms by which balance is controlled during complex walking. Control of the lateral acceleration of the COM, an aspect directly influencing walking balance, is a function of three mechanisms that we can quantify through biomechanical analyses: 1) foot-placement, 2) push-off, and 3) counter-rotation of the body segments. Although we know stroke alters lower-limb control and propulsive capabilities during walking, it is unknown how the contributions of these balance control mechanisms are affected by stroke. Furthermore, we do not know how the contributions of each mechanism may change with increased task complexity that constrains or places more demands on these mechanisms. Our study aims to 1) characterize the balance control mechanisms of those with and without chronic stroke during unconstrained walking, 2) characterize the balance control mechanisms of those with and without chronic stroke during complex walking tasks, and 2) determine how walking adaptability is related to balance control mechanisms in those with chronic stroke. To address the first aim, we will use biomechanical analyses to quantify the contributions of foot-placement and push-off in controlling the lateral COM acceleration during unconstrained walking. To address the second aim, we will use biomechanical analyses to quantify the contributions of foot-placement and push-off in controlling the lateral COM acceleration during narrow-path and fast walking tasks. To address the third aim, we will establish the relationship between the performance of complex walking tasks, and the change in contributions of the balance-control mechanisms utilized during those tasks in those with chronic stroke. The results of this study will provide evidence that balance mechanisms are different in those with chronic stroke, and that an inability to alter the contributions of those mechanisms during complex walking tasks may be a barrier to that task performance. This evidence would inform future work aimed at promoting safe community ambulation for those with chronic stroke by targeting balance control as a means for improving complex walking performance.
